Merlins > Packard vs RR

[fastmongrel]

They come out of the toolbox occasionally but they are mostly for sentimental purposes.

 

[nincomp]

(1) It is often said that this was because Packard Merlins were built to metric standards and required a completely different set of spares. However, those that restore and repair Merlins say that parts are interchangeable.

This is what I have heard, but it has always been second or third-hand information. If that is the case, the tool kit would be needed for the American, who would not have the correct tools. Another possibility would be that engine is a hybrid of sorts. Most of the parts would use the British standard, but some of the parts unique to the Packard (superchargers and carburetor maybe?) would use the American standard. In this last case, a tool kit containing a mixture of British Standard and American standard would be needed since few mechanics would both types handy. Fastmongrel, if your set of Packard-Merlin tools is complete, would you tell me which of my silly-assed scenarios are correct?*

Does anyone know for certain about the Packard engines? If Packard needed to retool in order to make British-spec engines, it makes sense that the initial production could be delayed.

In addition, what kind of threads did RR use? Would they be Whitworth threads, 60-degree threads, or some combination. This is not as stupid as it sounds since my Lee-Enfield No.4 Mk2 is such a hybrid according to some sources.**

* Is the crescent adjustable wrench a left-handed model and does it only work on British bolts?

** I do know that the barrel attaches to the receiver with Whitworth threads. I am too much of a weenie to disassemble the rifle to find out. The rifle is fairly rare as it is one of the last produced (1955), was never issued, and is unfired (except for its original proof-firing). If I damaged a screw or rounded the head of a bolt, I fear that I would a scream like a little girl. ***

*** If any of you need to have this rifle in order to live a fulfilled and happy life, contact me.

 

[wuzak]

I believe Packards used all British fasteners.

They would have been Whitworth, BSF (British Standard Fine) and BA (British Association).

There were differences between Packard and Rolls-Royce engines. The supercharger was the same design, but the supercharger drive on (some) 2 stage Packards was a Wright epicyclic unit, rather than the Farman system used by Rolls-Royce.

The main difference between those delivered to the US and those to the RAF was the propellor shaft. The US bound Packards had SAE splined shafts.

 

[Milosh]

Packards also used AC Delco magnetos. The carbs were different > Packard - Bendix, R-R - SU.

The prop spline was the SAE No.50

 

[GregP]

Interesting you should mention the splines. Joe Yancey made a prop adapter for engine break-in and it is 50 spine on the inside and 60-spline on the outside. Thus he can run either prop on an Allsion for break-in. Naturally, being a round, hollow cylinder shape, it is perfectly balanced as made, and very easy to use.

He has a WWII-era 6-blade Hamilton-Standard club prop, and it loads the engine just fine for break-in. When we first tried it, we set the pitch at 45° to start with and could not get it over 1,300 rpm. By the time we were done, the club was at 22.5° and we can get 2,500 rpm at 40 inches for break-in. When we called Hamilton for some data on the prop, they said that the prop was the property of the US Army Air Corps and since we weren't the USAAC, they would not give us any info!

Joe just used standard torque values for the grade 8 bolt sizes and it runs just fine. His break-in stand is a 2.5-ton Ford truck and he can pull the truck backwards, sliding on the tires, if he exceeds 50 inches!

 

[Frankenerd]

in service RR ones were found to be more powerful yet packard were found to have slightly better fuel economy.........

I would dispute this. It depends on which variation of each engine you talk about. No R-R Merlin placed in service in any mass produced aircraft made more than 2080 HP and that figure had to be backed down to 2030 HP for longevity reasons. The Packard V-1650-9 in the P-51H on the other hand made 2,218, or 2,220 HP, ( Depending on the info source!) with a TBO more than twice that demonstrated in the Hornet.
On the other hand, R-R Merlins made 1,710 or 1,720 HP when the equivalent Packard -7 only made 1,595 HP. While this looks to be significant, it was in fact just differences in the amount of throttle opening and Boost permitted in order to pass different longevity requirements. The Reduction gear also had something to do with these numbers.
As an aside, the Allison V-1710 made 1800 and 2300 horse power with slightly less blower boost and slightly better fuel economy than either version of the Merlin above, due to the splayed valves and pent-roof combustion chambers. What it lacked was backfire screens in the intakes because of political choices in Washington DC.

 

[tomo pauk]

<gets popcorn>

 

[Frankenerd]

That's interesting, in smaller recips, cars, bikes the key is to graduly vary thr rpms to avoid "setting" an engine in a particular rpm range. I had a guy bring me an old Honda bike for a tune-up, I found it would not rev beyond 4,500rpm because the owner never reved it beyond that, compression and tune were right on the numbers. The owner confirmed it was never reved higher and was very happy with the job said "It never ran better".

Break in time varies with the pistion ring type but I'll bow to your expertise - I'm ASE certified not A&P. Your much more familiar with aircraft.

wmaxt

Porsche claimed that >90% of all wear on the engine happened in the first 10 seconds after starting. At the Frankfurt Auto Show in 1972, they showed a car they claimed would last for 1,000,000 miles ( Km?) it had an electric oil pump that filled the galleries with oil before starting.
They also recommended that the break-in use varied throttle levels that included full blast sprints followed by longer periods of slow driving to let the engine cool. It was the hard use that broke it in and heat that damaged it. They claimed that a good break in only required about 100 miles.

 

[Frankenerd]

So which are you claiming, that the Merlin wasn't reliable in 1941, or that is wasn't being mass produced?

The answer is that it was relaible and in mass production, so the argument that it was Packards input that made that possible falls down.
No, the simple statement above misses the point. During the entire war, R-R only built about 32,000 engines in their original plant. In about half that time, Packard built ~56,000. So no R-R did not learn how to build the Merlin at the same rate Packard did.
Then there is the quality argument. R-R Merlins were expected to last ~100-125 hours in a Spit, or Hurry and 2-300 hours in a bomber. Power ratings were 1350 in fighters, but the bombers only made 1280. The Packard was required to last 3-400 hours in fighters, but often went twice to three times that long in Lancs. later in the war when the Fw-190 was such a shock, they used 115/150 Octane gas and more boost to give the 66 Series Merlins 1,710-1,720 HP. Longevity went down to where some in "diver patrol squadrons did not last 25 hours! We flew some 1,595 HP Packard's for 800 hours in Mustangs and P-40s sent to Russia. No R-R Merlin, even those built post war went that long.

There's no doubt of that. But it's a huge stretch to go from that to claiming that Packard was required to productionise the Merlin, and to improve it's reliability, when both had been done long before Packard became involved. The myth of Rolls Royce craftsmen hand building, and hand fitting, Merlins until Packard came along is just that, a myth.
Well, no it is not. The post war Merlins used in civil transports still had "Hand file to fit." in their erection manual! That phrase never appears in the Packard manual.

It's also true that the British motor industry carried out the same functions. For example, it was largely the car inductry that mass produced the Bristol Hercules, turning out close to 60,000 of them before the end of the war. Morris cars created the Castle Bromwich Spitfire plant, that produced more than 15,000 Spitfires during the war.

Don't forget, Britain, with just over half the population of Germany, produced more aircraft, and far more in terms of weight, and far more aero engines, whilst employing less workers in the aircraft industry than Germany.
All true!

Of course not, America was a much larger country, with far more people, and far more cars. But it's a huge, and unwarranted, jump to go from saying America produced more cars than anyone else to saying only America could mass produce with quality. The historical record is that in the late 30s Rolls Royce developed the Merlin for mass production and sorted out the quality.
I would ask why if they were so good, did they have half the TBOs of Packard built engines?

If you want to claim Packard was responsible for this, you have to show that the Merlin was either unreliable before Packard became involved (ie in 1940 and 1941) or not being mass produced. Neither is true.

I guess it's all a mater of scale and how you define reliability. Durability?

 

[Frankenerd]

Twithch, do you have a source for where I can find more info on how the Packard engines were made and tested, etc.? I have books that mention the production figures and outputs and the normal statistics, but not anything about how the motors were assembled/tested. Actually, does anyone have information on other engines as well, i.e. Jumo, Allison, BMW, etc?

My Grandfather's next door neighbor was a Government QC Inspector for Piston engines. He would routinely pick one and run it flat out for the entire 150 hours it was supposed go at varied throttle openings. They hated him at the engine plants, but he did not care. he said our boys are going to fight in those planes and they better be the best we can make them.

 

[Frankenerd]

This Twitch fellow is unfortunately a typical American, i.e. a brainwashed idiot. First, by comparing American war production to the pre-war production, it was no better than that of the UK or Germany. That is according to a recent study published by University Press of Kansas. Second, Packard intruduced NO improvements on the Merlin, not a single one. Third, Packard had to change the blueprints for their workforce was composed of typical Amis as described above whereas RR had SKILLED workforce who could think with their own brains.

Not true. We introduced MW-50 ADI!

 

[pbehn]

I guess it's all a mater of scale and how you define reliability. Durability?

Your edit seems to confuse planes in the fw190 "shock" era 1941 with diver (anti V1) patrols 1944.

 

[tomo pauk]

Yay!
Shooter is back.

 

[Shortround6]

Yay!
Shooter is back.

Yep, the red color is near sure tell tale.

 

[fastmongrel]

I see our very own village idiot is back.

 

[fastmongrel]

Yep, the red color is near sure tell tale.

Dont forget the poor spelling and crazy grammar

 

[DerAdlerIstGelandet]

Is that you shooter?

 

[FLYBOYJ]

Frankenerd - you realize that you're replying to threads that are over 10 years old and that some of those members aren't even around anymore?!?!?

 

[bobbysocks]

the thread has been ageing like a fine wine...just waiting for the a particular stroke of brilliance to weigh in.

 

[KiwiBiggles]

I checked in to this page to see if anything else amusing had come in. The first entry on this page, made three years ago, is prescient:

"They come out of the toolbox occasionally but they are mostly for sentimental purposes"

Admit it, you miss Shooter when he's not around.